This application is based on Japanese Patent Application No. 2001-100309 filed on Mar. 30, 2001, the disclosure of which is incorporated herein by reference.
The present invention relates to a fuel injector of an internal combustion engine.
It is recognized that heating of fuel during cold engine starting will reduce harmful components in exhaust gas. In a fuel injector, a heating element is generally provided radially outside of a vale body to heat fuel in the valve body and atomize it during cold starting. As the heating element, a ceramic heater is widely used. In a fuel injector 100 shown in FIG. 8, for example, a valve member 101 opening/closing a valve seat orifice has a cylindrical shape having a bottom. A valve body 103 encloses the valve member 101 and supports it to reciprocate. A ceramic heater 102 in the cylindrical shape is provided on the outer periphery of the valve body 103.
It is an object to provide a fuel injector in which fuel is effectively heated and atomized.
It is another object to provide a fuel injector in which a ceramic heater is mounted without being damaged.
It is a further object to provide a fuel injector in which a ceramic heater is tightly fitted to improve heat conductivity.
It is a still further object to provide a fuel injector in which fuel is effectively heated irrespective of variation in the size of a ceramic heater.
According to one aspect of the present invention, a plurality of ceramic heaters is provided on the outer periphery surface of a valve body. Each of the plurality of ceramic heaters has an arc shape in cross section and arranged in a circumferential direction to surround the outer periphery of he valve body. According to this, the plurality of ceramic heaters is mounted without being damaged and tightly fitted on the outer peripheral surface of the valve body. Ther fore, heat from the plurality of ceramic heaters is effectively conducted to the valve body. As a result, fuel in the valve body is effectively heated.
According to another aspect of the present invention, a heating element is press fitted in a holder and the holder is press-fitted to a valve body. The valve body defines a fuel passage therein and a valve member is supported in the valve body to reciprocate in an axial direction. Accordingly, it is not necessary to press-fit the ceramic heater on the valve body. Since the holder contacts both of the heating element and the valve body, heat from the heating element is not only directly conducted to the valve body but also conducted to the valve body through the holder. Therefore, the fuel is effectively heated.